'The medium is the message' means that its not the specific content of new media that's important, but rather the very nature of the media itself, and the way media extend the reach of human beings in various ways.

A major concept in the book is how certain media fragment, or individualize society, while others integrate, or re-tribalize society. McCluhan's most exemplary fragmentary medium is literacy, especially alphabetic literacy, and especially alphabetic literacy after moveable type printing. He cites television, and presumably the web of electronic media that was to follow, as an integrating 're-tribalizing' medium, psychologically interconnecting all humans in a society the way old oral traditions did before societies were fragmented by the individuality of lone reading and thought.

An interesting premise. I’m not sure how the hot/cool media dichotomy ties into the fragmenting/integrating dichotomy. Perhaps I need to read Understanding Understanding Media.

Marshall McLuhan was a man with a lot of ideas. He was also someone who had great popular appeal for a short period of time during the 1960s and 1970s, and has since receded from both popular and academic discourses. It is entirely in keeping with his own thinking to attribute this trajectory of influence to the genre and style in which he wrote.

McLuhan’s writing style is informal but nonetheless extremely dense and rather difficult. Although he was a professor of English who had been teaching for two decades by the time he began publishing his theories of media in the early 1960s, McLuhan’s books do not follow academic conventions. Rather, Understanding Media might best be approached as an extended critical essay on the social role of technology, a work of social theory rather than history or empirical sociology. McLuhan’s sources range from popular historians such as Arnold Toynbee and Daniel Boorstin to fellow public intellectuals like Lewis Mumford to journalism appearing in Life magazine and The New York Times. His background as a scholar of literature is also in evidence, with extensive quotes from Shakespeare and poets of the 19th and 20th centuries. Curiously, McLuhan never cites Harold Innis, the economist and fellow Canadian who he and several of his students later described as the strongest influence upon him.

Understanding Media is about 300 pages long, but the first thirty pages or so of the text communicate the main ideas for which McLuhan became famous, ideas which became attached to aphorisms he coined such as “the medium is the message.” His argument is first that technologies in and of themselves communicate cultural values: a medium itself has a message independent of that which its user intends to communicate. The canonical example of this for McLuhan—an example he develops throughout this book and his earlier The Gutenberg Galaxy—is print. Any given printed book communicates its contents, of course, but it also communicates a cultural logic associated with the book itself.

This is an argument at the core of McLuhan’s historical thought that deserves a little more attention, particularly in regards to the ways that other theories of the politics of technology depart from McLuhan. It has become widely accepted in the history of technology that technologies favor particular social orders, and indeed that technologies can embody and reify existing social relationships. McLuhan accepts the first proposition but not the second. Rather, for McLuhan technologies are themselves agents that cause revolutionary social changes unintended by their inventors. He is thus very interested in the personality of the printing press, but not at all interested in Gutenberg himself or the social circumstances that produced him.

The particular social changes McLuhan ascribes to print are as intriguing and controversial as the process he describes. Print, he writes, displaced an earlier oral culture which was organic and decentralized in social structure. The argument that the availability of common texts made nationalism, collective identity, and the nation state possible both predated and outlasted him, but McLuhan adds that the logic of reproduction communicated by printing many copies of the same thing made possible mechanization. The printing press was not a product of industrialization, in other words, but its cause. This same social transformation also produced the concept of the individual, though the mechanism by which it does so is somewhat obscure. (McLuhan seems to avoid positive references to dialectical reasoning, perhaps motivated by anticommunism.) He ascribes one other curious effect to print, though: the development of the idea of the infinite, and thus of major changes in mathematics and art. Infinity, he argues, could only be conceived of once mechanical reproduction existed and people could imagine the continuation of this process beyond its actual duration.

The 20th century, according to McLuhan, was the period of the next great media revolution, brought about by electricity, which he also credited with numerous social effects. The speed of electrical communication, according to McLuhan, demolishes distinctions between center and periphery (or center and margin, in his terminology). It decentralizes social structures, flattens hierarchies, leads to broader political participation. It was these optimistic visions of the present and future, and particularly of television, which many of McLuhan’s readers found most appealing about his work.

One point of McLuhan’s which might not have found much of an audience is his argument that new technology brings with it a numbness and apathy toward the very social change it engenders. Society ought to be guided, he writes, by the moral perspective afforded by art and literature, as well as by critical studies of media itself. Although he believed that much of the change brought about by television and other electronic media was either good or inevitable, McLuhan also sought to warn us of its dangers.